1. Field of the Invention
The present invention relates to a pen-input panel or a touch panel which is used for input to a personal computer, a word processor, an electronic notepad, etc.
2. Description of the Related Art
A resistance film type touch panel which is used by being placed on a display such as an LCD, a PDP, or a CRT is known. This type touch panel includes a pair of panels, each having a transparent conductive film adhered on a transparent board, which are arranged via electrically insulating spacers so that the conductive films are opposed to each other. Circuits are connected to electrodes which are formed on each of the conductive films, and thereby coordinates can be detected by pushing one of the boards by a pen or finger to allow conduction between the upper and lower panels.
The touch panel has being used in large quantities in many fields with the development of electronic equipment and, accordingly, a touch panel capable of being produced more simply and having more durability is strongly required.
For example, for the upper panel and the lower panel of the two transparent panels, a film and a glass, a film and a plastic panel, a film and a film, or the like have been used and, for the conductive film, ITO (indium oxide/tin oxide) or tin oxide (SnO2) is used. However, the conductive film adhered on the board is required to be divided into a desired pattern, and hence prior art touch panels have been formed by eliminating unnecessary portions by etching after adhering a conductive material on the entire surface of the board by sputtering, etc.
For the etching, photolithography methods and sandblast methods have been used. The photolithography methods are classified into, according to etching material, wet methods using a liquid such as aqua regia or hydrochloric acid, and dry methods using a gas such as hydrofluoric acid (HF) or iodinefluoric acid (HI). The wet method requires many processes such as photosensitive resin coating, drying, exposure development by photomasking, and drying, and requires a significant capital investment for liquid control and waste liquid treatment because dangerous liquid such as aqua regia and hydrochloric acid are used. The dry method also requires a significant capital investment for measures against gas leaks, treatment of exhaust gases, etc. because dangerous gases such as hydrofluoric acid and iodinefluoric acid are used.
In addition, there is a method of eliminating unnecessary parts by sandblasting. This method has problems in that much process time is required, many man-hours for management are required due to necessity of frequent exchange of the mask covering the necessary parts, and the strength is reduced due to damage to the board. For this reason, a touch panel having a conductive film divided by a simple operation and entailing a small facility cost is strongly required.
An upper panel and a lower panel of the touch panel can be adhered to each other via a double-faced tape at their perimeters, but they are sometimes damaged by the edge of the double-faced tape when the panel surface is pushed. For this reason, a durable touch panel which does not suffer such damage is required.
In addition, an optical material is often adhered on the surface of the touch panel via an adhesive layer, but these are sometimes peeled off from each other for adhering them again when foreign materials or bubbles enter therebetween during the adhering work. The touch panel and/or the optical material are sometimes damaged, so that they cannot be used again. For this reason, a touch panel having an optical material so adhered thereto that they can be used again after peeling them off from each other.